House Speaker John Boehner leaves a news conference on Capitol Hill in Washington, Thursday, Feb. 17. Boehner says, "“These are going to be the most important two, three, four months that we have seen in this town in decades."

When the gavel finally banged down after 4:30 a.m. Saturday morning in the US House of Representatives and lawmakers wobbled off to bed after a series of all-nighters, it wasn’t the end of the battle to keep the federal government from shutting down on March 4.

Barely the beginning, in fact.

They’d passed a continuing resolution to keep federal agencies operating through the end of FY 2011 (Sept. 30). But in cutting $61 billion from current spending levels through that period, they’d taken mighty whacks at many popular programs – eliminating some – in a way sure to set up confrontation with the Democrat-run Senate and the Obama administration.

The $1.2 trillion stop-gap measure passed by the House in fact is just the opening round in what’s likely to be a major partisan fight through the rest of this Congress and Obama’s White House term over government spending, taxation, major entitlements like Social Security, raising the federal debt limit, and reducing the $1.6 trillion deficit.

With a newly-powerful GOP now running the House (prodded sharply from the right by its tea party wing and 87 independent-minded freshmen) and the next presidential election campaign just months away, it’s likely to be particularly intense.

“These are going to be the most important two, three, four months that we have seen in this town in decades," House Speaker John Boehner said during Saturday’s wee morning hours. "It's all one fight."

The spending bill passed 235-189, virtually along party lines. (Three Republicans joined Democrats in voting “no,” two of them because they thought the spending cut wasn’t deep enough.)

The bill cuts spending in ways that reflect the political and ideological divide over important issues and controversial programs.

Regulators dealing with financial reform and consumer protection were targeted, as well as foreign aid, education, nutrition programs, and heating and housing subsidies for the poor.

In all, reports the Washington Post, it would be “the largest rescission of federal funds since the conclusion of World War II.”

Interest groups and Democrats were quick to react, the White House warning that retirees may not get their Social Security checks if the government shuts down less than two weeks from now.

"This is like a Cliff Notes summary of every issue that the Republicans, the Chamber of Commerce, and the [free market] CATO Institute have pushed for 30 years," said Rep. Edward Markey, (D) of Massachusetts.

Environmental advocates were particularly outraged.

“This atrocious anti-environmental bill attacks the Clean Air Act and Clean Water Act,” said Anna Aurilio of Environment America. “It wipes out future funding for common-sense home weatherization programs, and threatens to impose the largest overall percentage cut to EPA’s budget in 30 years.”

As the clock ticks toward the March 4 deadline for current government funding, the measure now heads to the Senate.

There’s some talk of a temporary spending measure to keep the government operating through March while the two sides work things out for the rest of the fiscal year. But given the wide political split at the moment, that only delays the inevitable.